Background: Coronary heart disease (CHD) is a leading cause of death in Canada; however, physical activity (PA) has been shown to reduce mortality. Unfortunately, CHD patients are not engaging in enough PA. Purpose: To explore the association of the environmental variables (a) rurality, (b) access to PA opportunities, and (c) community socio-economic status (SES) with PA in CHD patients 3 months after discharge? And how does task self-efficacy may mediate these associations Results: Regressions showed that task self-efficacy predicted PA; however rurality, and SES did not predict PA at 3 months, nor did access to PA opportunities with the exclusion of pools. The lack of associations required no mediational analyses to be performed, except for pools, which demonstrated no mediational influence from self-efficacy. Conclusion: While task self-efficacy was a key PA correlate, there were no associations between the environment and PA (with the exclusion of access to pools).

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The effects of a twelve-week low-intensity exercise conditioning program on blood pressure (BP), heart rate (HR), rate-pressure-product (RPP) and cardiac autonomic function were examined in menopausal and post menopausal women with hypertension. Eligible participants (n=50) were counterbalanced to either the exercise group or the control group. Using a pretest-posttest design, participants were tested at the beginning and the end of the 12-week study period, in which BP, HR, RPP, heart rate variability and spontaneous baroreflex sensitivity were measured at rest and during standing and low intensity steady-state exercise. The exercise group participated in a 12-week, low-intensity walking program, 5 days/week, while the comparison group continued with usual activity. The exercise group adhered to 4 walking sessions per week while the control group averaged 0.6 walking sessions per week. Repeated measures analysis of variance (ANOVA) demonstrated a reduction in systolic and diastolic BP and RPP in hypertensive women. Additionally, the low intensity exercise conditioning program attenuated the physiological response to stress (standing, exercise). This was evidenced by decreased systolic and diastolic BP and RPP in the exercise group and increased diastolic BP in the control group. Postmenopausal women demonstrated decreased log transformed high frequency power and total power in comparison to menopausal women. However, postmenopausal women also showed decreased low frequency power in comparison to menopausal women. It was concluded that a 12-week, low-intensity exercise conditioning program reduced systolic and diastolic BP and RPP in hypertensive women while attenuating their physiological responses to stress. / Thesis (Master, Nursing) -- Queen's University, 2008-09-25 21:46:53.32

Considering the increasing global prevalence of overweight and obesity and their propensity for disease, this study was undertaken in an attempt to optimize exercise prescription for this at-risk group by determining if the benefits associated with interval training occur in an intensity dependent manner. 19 sedentary, overweight males (Age: 22.7 ± 3.9 yrs, BMI: 31.4 ± 2.6 kg/m2, WC: 106.5 ± 6.6 cm) performed interval training for three weeks at either 70% or 100% of their peak work rate on a cycle ergometer. Aerobic capacity measurements, time to completion trials, muscle biopsies, and fasted blood samples were all performed pre and post training. Analyses of aerobic capacity and exercise performance demonstrate greater improvements made in the 100% compared to the 70% group, while measures of skeletal muscle oxidative capacity indicate equivalent changes between groups. Taking into account the similar increases in mitochondrial content in both groups and understanding the influence of both oxygen supply and demand in determining maximal oxygen consumption, the greater increases in aerobic capacity achieved by the 100% group may be the result of enhanced cardiovascular adaptations. These findings suggest that some of the health benefits associated with interval exercise may be intensity dependent. Therefore, there may be additional benefit to exercise at higher intensities. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2012-09-27 17:26:19.425

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The effects of differing recovery patterns following intermittent exercise on blood lactate and subsequent performance were examined. Fourteen male subjects completed three randomly assigned experimental protocols. Each protocol consisted of eight 45s-bouts of cycling on a Monark cycle ergometer at 120% of VO$ sb2$ max interposed with five minute recovery periods. Each protocol ended with a maximal performance task consisting of a 45s all-out cycling test. Recovery patterns included passive, cycling (45% of VO$ sb2$ max), and arm cranking (45% of VO$ sb2$ max). Results revealed similar blood lactate concentrations in the passive and arm cranking conditions but significantly lower (p $<$.05) levels in the cycling condition. Mean power outputs measured from the performance task were significantly higher (p $<$.05) in the cycling and arm cranking recovery conditions. The correlation between blood lactate levels and mean power output was low (r = $-$0.28), suggesting that other factors were influencing subsequent performance.

Obese females face a number of health challenges, including infertility. Obese females are three times more likely to present with infertility compared to normal weight females. Exercise improves infertility by interacting with hormones specific to reproduction. The hormones leptin and kisspeptin (KiSS) are crucial for reproduction. Research suggests leptin may increase production and secretion of KiSS. KiSS subsequently increases gonadotropin-releasing hormone, activating the menstrual cycle and reproduction. Interestingly, circulating levels of leptin and KiSS are altered in the obese state. Leptin levels significantly increase, whereas KiSS levels decrease. Studies demonstrate increases in leptin cause leptin resistances, which is followed by a decrease in KiSS mRNA concentrations. Exercise is associated with decreases in circulating leptin and infertility, however there is no research examining the changes in KiSS after an exercise intervention. Therefore the purpose of this research was to examine the effects of an exercise intervention on circulating KiSS and leptin levels in obese females. Ten obese females were randomized to an exercise intervention (n=5) or a non-exercise control group (n=5). The exercise intervention group completed a 12-week supervised, progressive, aerobic exercise program that involved walking a treadmill between 65 – 75% of their predicated maximum heart rate. The non-exercise control group maintained their current lifestyle habits. All participants had blood drawn at three different time points; baseline, mid-point and end-point; and KiSS and leptin levels were analyzed. The exercise group had a significant decrease in %BF (p<0.01) compared to the control group from baseline to end-point testing, whereas there was a significant increase in weight (p<0.01) and BMI (p<0.01) in the control group from baseline to mid-point testing. A group main effect for circulating leptin levels was found (p<0.01), however a pairwise comparison between the exercise and control group was not significant (p=0.81). For KiSS there was a main effect of time (p<0.05). Test of Within-Subjects Contrasts indicated that there was a significant decrease in KiSS between baseline and end-point testing (p=0.05). Individual participant data was also graphically represented for weight, leptin and KiSS level. Trends in the data suggest leptin levels in the exercise group corresponded with changes in weight; as weight decreased from baseline to mid-point testing, so did leptin levels. When individual participant KiSS levels were looked at in conjunction with leptin changes over the intervention potential trends did appear. All exercise participants experienced decreases in leptin from baseline to mid-point testing and all but one exercise participant saw increases in KiSS levels during the same time frame. Overall, results support a decrease in %BF in the exercise group compared to the control group. However, there was no evidence to support that an exercise intervention for obese females statistically significantly decreased circulating leptin levels and increases KiSS levels. Although there was a trend for hormone levels to be associated with body fat levels, the small sample size was problematic. A definitive study with increased numbers is now required to elucidate whether the trends become significant.

Obesity, through a persistent positive energy and fat balance is of major public health significance due to its detrimental health, social and financial costs. Increasing physical activity levels through recreational exercise and decreasing energy intake have been implicated with obesity prevention. However, the addition of exercise to normally sedentary routines will only prevent positive energy balance if it is not tracked b a compensatory response in energy intake and non-exercise physical activity [also termed non-exercise activity thermogenesis (NEAT)]. The current series of studies set out to examine the quantitative and temporal relationship between exercise and energy balance with specific reference to appetite, energy intake and NEAT. These studies were designed using similar methodologies that could be compared and related to existing studies. The results showed that in younger motivated individuals, moderate-high intensity mandatory exercise increased daily energy expenditure leading to a marked negative energy balance. However for periods of up to two weeks, analysis of temporal trends revealed evidence of compensatory changes to re-establish energy balance (re-equilibrium phase). This re-equilibrium was a result of not only increases in energy intake, but also (and to a greater extent) decreases in NEAT. Inter-individual variability in the extent of compensation was evident and independent of age, sex, BMI and restraint status. Decreases in physical activity did not lead to a compensatory reduction in energy intake and lead to a marked positive energy balance. Using an exercise intervention, in line with government guidelines, in a group venerable to becoming obese showed that body mass was largely unaffected since overall energy expenditure was not significantly elevated, primarily due to a lack of motivation to reach the required exercise prescription. The results have public health significance in the formation of policy to increase physical activity in the population.

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